Cooling system for vehicle

Abstract

In a cooling system for cooling a heating element mounted in a vehicle, a radiator is located at a position higher than a heat sink, which absorbs heat from the heating element. When the amount of heat generated from the heating element, which is detected by a sensor, is greater than a predetermined first value, a blower is operated. Further, when the detected amount of heat is greater than a predetermined second value that is higher than the predetermined first value, a pump is operated. When the detected amount of heat is equal to or less than the predetermined first value, the pump is stopped and the cooling water is circulated by a principle of heat siphon. Accordingly, power consumption of the pump is reduced. Further, power consumption of the cooling system is reduced or an increase in power consumption of the cooling system is restricted.

1. A cooling system for cooling a heating element, the cooling system comprising:
 a heat sink through which a cooling fluid passes to absorb heat from the heating element; 
 a radiator communicating with the heat sink through a cooling fluid circuit through which the cooling fluid flows, wherein the radiator radiates the heat of the cooling fluid and is located at a position higher than the heat sink; 
 a pump portion that is arranged between the heat sink and the radiator in the cooling fluid circuit and pumps the cooling fluid to circulate the cooling fluid through the cooling fluid circuit; 
 a bypass passage that is arranged in the cooling fluid circuit to bypass the pump portion, wherein when operation of the pump portion is stopped, the cooling fluid flows in the radiator through the bypass passage while bypassing the pump portion; and 
 means for controlling the pump portion, wherein 
 the pump portion is stopped by the means for controlling the pump portion when an amount of heat generated from the heating element is equal to or less than a predetermined value, and the pump portion is operated by the means for controlling the pump portion when the amount of heat generated from the heating element is greater than the predetermined value. 
 
   
   
     2. The cooling system according to  claim 1 , further comprising:
 a blower for creating a flow of air toward the radiator; and 
 means for controlling the blower, wherein 
 the blower is stopped by the means for controlling the blower when an amount of heat generated from the heating element is equal to or less than a predetermined value, and the blower is operated by the means for controlling the blower when the amount of heat is greater than the predetermined value. 
 
   
   
     3. The cooling system according to  claim 1 , further comprising:
 a blower for creating a flow of air toward the radiator; and 
 means for controlling the blower, wherein 
 the blower is stopped by the means for controlling the blower when an amount of heat generated from the heating element is equal to or less than a predetermined first value, and the blower is operated by the means for controlling the blower when the amount of heat is greater than the predetermined first value, and 
 the pump portion is stopped by the means for controlling the pump portion when the amount of heat is equal to or less than a predetermined second value that is greater than the predetermined first value, and the pump portion is operated by the means for controlling the pump portion when the amount of heat is greater than the predetermined second value. 
 
   
   
     4. The cooling system according to  claim 1 , further comprising:
 a blower for creating a flow of air toward the radiator; 
 air-blowing amount controlling means for controlling an amount of air blown by the blower based on an amount of heat generated from the heating element; and 
 the means for controlling the pump portion controls a circulation rate of the cooling fluid circulated by the pump portion based on the amount of heat generated from the heating element. 
 
   
   
     5. The cooling system according to  claim 4 , wherein
 the means for controlling the pump portion stops an operation of the pump portion when the air-blowing amount of the blower is less than a maximum level. 
 
   
   
     6. The cooling system according to  claim 5 , wherein
 the means for controlling the pump portion increases the circulation rate of the cooling fluid circulated by the pump portion with an increase in the amount of heat of the heating element when the air-blowing amount of the blower is on a maximum level. 
 
   
   
     7. The cooling system according to  claim 1 , wherein the heating element is an electrical device mounted in a vehicle. 
   
   
     8. The cooling system according to  claim 1 , wherein the heating element includes a driving electric circuit for driving a driving motor of a vehicle. 
   
   
     9. The cooling system according to  claim 1  mounted in a hybrid vehicle that is driven by an electric motor and an engine. 
   
   
     10. The cooling system according to  claim 1 , further comprising a check valve that is arranged in the cooling fluid circuit to prevent the cooling fluid from flowing backward through the bypass passage from a discharge side of the pump portion to a suction side of the pump portion. 
   
   
     11. The cooling system according to  claim 1 , further comprising flow regulating means for limiting a flow of the cooling liquid in the bypass passage from a radiator side end of the bypass passage to a heat sink side end of the bypass passage while enabling a flow of the cooling liquid from the heat sink side end of the bypass passage to the radiator side end of the bypass passage. 
   
   
     12. The cooling system according to  claim 11 , wherein the pump portion is arranged between an outlet of the heat sink and an inlet of the radiator. 
   
   
     13. The cooling system according to  claim 12 , wherein:
 the radiator side end of the bypass passage is located between an outlet of the pump portion and the inlet of the radiator in the cooling fluid circuit; and 
 the heat sink side end of the bypass passage is located between an inlet of the pump portion and the outlet of the heat sink in the cooling fluid circuit. 
 
   
   
     14. The cooling system according to  claim 11 , wherein the cooling fluid circuit provides an unobstructed passage that directly connects between an outlet of the radiator and an inlet of the heat sink. 
   
   
     15. The cooling system according to  claim 1 , further comprising:
 a blower for creating a flow of air toward the radiator; wherein 
 the means for controlling the pump portion also controls the blower; 
 when an amount of heat generated from the heating element is equal to or less than a first predetermined value, the control means stops the blower and the pump portion; and 
 when the amount of heat generated from the heating element increases beyond the first predetermined value, the control means first operates the blower without operating the pump and then operates the blower and the pump upon further increase of the amount of heat generated from the heating element. 
 
   
   
     16. The cooling system according to  claim 15 , further comprising temperature sensing means for sensing a temperature of the cooling fluid, wherein:
 the control means stops the blower and the pump portion when the sensed temperature of the cooling fluid, which is sensed by the temperature sensing means, is equal to or lower than a predetermined first level; 
 the control means operates the blower and stops the pump portion when the sensed temperature of the cooling fluid is higher than the predetermined first level and is equal to or lower than a predetermined second level that is higher than the predetermined first level; and 
 the control means operates blower and the pump portion when the sensed temperature of the cooling fluid is higher than the predetermined second level. 
 
   
   
     17. The cooling system according to  claim 16 , wherein the temperature sensing means is a temperature sensor arranged in the cooling fluid circuit.